Packaging materials for products such as food, film, chemicals, and other goods may incorporate metal foil, polymeric and/or adhesive layers of material. See, for example U.S. Pat. Nos. 4,119,479; 4,363,841; 4,556,590; 4,567,112; 4,613,536; 4,778,712; 4,806,398; 4,948,640; 4,956,210; 5,077,104; 5,098,751; 5,759,422; and 6,083,628. See also an article by J. D. Affinito et al entitled “PML/oxide/PML barrier layer performance differences arising from use of UV or electron beam polymerization of the PML layers”, published in Thin Solid Films, 308-309, (1997), pp. 19-25 by Elsevier Science S.A.
Filter cigarettes are typically sold in packages containing about twenty cigarettes. The packages are generally rectangular, in the form of “hard packs”, “crush proof boxes”, “hinged lid packages”, or “soft packs.” The packages are normally packed in cartons with typically ten packages to a carton. The polymeric overwrap material typically includes an oriented polypropylene. See, for example, U.S. Pat. Nos. 3,952,868; 4,163,684; 4,220,847; 4,250,994; 4,286,712; 4,293,068; 4,386,925; 4,789,060; 4,807,745; 5,249,676; 5,333,729; and 5,427,235.
Conventional cigarette packages are designed to maintain the freshness and moisture content of the cigarettes and to protect the cigarettes from adverse environmental conditions which decrease the freshness and quality of the cigarettes. Cigarette packages typically include three separate wrappings: (1) an inner foil liner comprising a metal foil laminated to a paper substrate or a metallized paper which is wrapped about the cigarettes and folded, but not sealed, at the ends of the cigarettes; (2) a “soft” or “hard” paper or paperboard package which is usually imprinted with brand specific information; and (3) an exterior clear overwrap of a heat sealable polymeric film which is heat sealed.
“Tear tapes” are commonly provided for easy opening of the polymeric overwrap films. When the top of the package is opened, the foil inner liner is torn open in the case of the soft pack or the hinged lid of the hard pack is pivoted open and a portion of the foil inner liner is removed to expose the ends of the cigarettes.
Under normal storage conditions, conventional cigarette packages are capable of maintaining the freshness and moisture content of the cigarettes at an acceptable level for a limited period of time. Thus, if the cigarette packages are stored too long, or if the cigarette packages are stored in unusually hot and/or dry atmospheric conditions, the conventional package does not adequately preserve the freshness and moisture content of the cigarettes.
Various flavoring components have been incorporated into tobacco products. Menthol is a common flavor component. The high degree of volatility and ease of sublimation of flavoring components such as menthol in tobacco products have presented problems in cigarette manufacturing operations, and have resulted in a decreased shelf-life of the products due to losses of flavorant by evaporation on storage.
On long term shipping and/or storage, cigarette packages are often subjected to relatively high temperatures (i.e., in excess of room temperature) for extended periods of time. This exacerbates the problems associated with conventional packaging in maintaining desirable levels of the flavor components.
One method for preventing premature volatilization of a smoking composition flavorant additive is by encapsulating the flavorant in microcapsules. A limitation of this technique is that the microcapsules tend to separate from the fillers and produce products with variable quantities of flavorant.
The foil inner liner of conventional cigarette packages has a primarily decorative purpose, and provides little or no barrier to the passage of oxygen and moisture between the cigarettes in the pack and the surrounding atmosphere. However, one approach for reducing the permeability of the foil is by laminating the foil with a thin layer of polyvinyl chloride. However, on long term shipping and/or storage, the foil liner tends to yellow over time, resulting in a package that is commercially undesirable. Further, flavorings such as menthol are often applied to the foil in the form of alcohol solutions, which can react with aluminum and adversely affect conventional cigarette packaging on long term exposure to relatively high temperatures.
U.S. Pat. No. 4,807,745 to Langley et al. discloses a heat sealed barrier package for cigarettes. The package material comprises a relatively thick laminate made of a foil layer to which two layers of biaxially oriented polypropylene homopolymer are adhesively bonded on opposite sides. Exterior and interior surface layers of a heat sealable thermoplastic polymer are applied, resulting in a laminate having a thickness of between about 1.5 to about 2.5 mils. The laminate is purportedly useful as an overwrap for a soft or hard pack or as a sealed inner liner for a soft or hard pack.
While the package of Langley et al. provides a more effective barrier than a single layer of foil, it would be advantageous to provide packaging materials which further reduce the permeability of moisture and oxygen through the packaging material.
It is therefore an object of the present invention to provide new packaging materials for cigarettes and other tobacco articles that are better able to withstand the conditions associated with long term shipping and/or storage. It would be particularly desirable to provide packaging materials for tobacco articles which include volatile and/or heat sensitive flavor components which minimizes the loss of the volatile and/or heat sensitive flavor components without undergoing a significant degree of discoloration.